Volume-03 ISSN: 2455-3085 (Online) Issue-12 RESEARCH REVIEW International Journal of Multidisciplinary December -2018 www.rrjournals.com [UGC Listed Journal] Biology of acridid grasshopper, Chrotogonus trachypterus Blanchard -A review Shashi Meena Assistant Professor, Department of Zoology, University of Rajasthan, Jaipur (India) _____________________________________________________________________________________________________________________ Grasshoppers are abundant and most diverse group of was studied by various workers [1, 17]. Observations were also insects worldwide. They are ployphagous in nature and made on population density, seasonal history and number of become voracious foliage feeder when occupying maximum generations, food preferences, development on different food population density [29, 30]. Grasshoppers, belong to family plants, nature and extent of damage caused by C. trachypterus ‘Acrididae’, order Orthoptera, feed voraciously on green plants in Punjab [6]. Patterns of variation in external morphology, and vegetation, throughout India and other parts of the world biology and ecology of immature and adults of C. trachypterus and cause severe damage. They consume considerable was also illustrated [5, 11, 12]. amount of foliage during their nymphal stage and damage millets, vegetables, cereal, citrus and ornamental plants. The eggs of acridids in general are slightly curved in the Migratory grasshoppers can also attack on other shrubs and middle and blunt at the ends and are enclosed in a frothy plants and consume all parts of them [14]. secretion of accessory glands and laid eggs at a depth of 4.81± 0.09 cm [9, 13, 32, 33, 34]. C. trachypterus on an Surface grasshopper, Chrotogonus trachypterus average laid 71.10±24.54 eggs. The highest fertility of eggs Blanchard is a polyphagous pest and occurs through the year was observed at fluctuating temperature but in contrast C. in semi arid area and damage wide variety of crops in seedling trachypterus laid 193.5±9.45 eggs at 32 ±2 °C [3, 4]. Females stage. The nymphs and adults both feed on leaves and tender of C. trachypterus deposit eggs in clutches inside the moist shoots of plants. The damage is sometimes so severe that soil, the female digs a hole in the moist soil by means of its repeated sowings are required [10]. A comprehensive revision ovipositor, inserts its whole abdomen in the soil and deposits of genus has been published by Kevan [15]. The important the eggs and insheaths them with glutinous secretion of host plants of this pest are jowar, maize, groundnut, collateral glands, which on hardening form a water-proof egg sugarcane, millet etc. [6, 22]. C. trachypterus was found to be pod with porous protection. Eggs are laid in the moist sand at a one of the serious pest of rice crop [16, 17], comparative attack depth of 4.2 to 5.5 cm with an average 4.81±0.41 cm. Prior to at seedling stage of different cotton varieties [31], abundance oviposition sand was examined by the female with the help of was monitored on rice variety IRRI-6 at Rice Research its antennae and ovipositor. Afterward, it stretched the sand Institute, Dokri during summer [18]. It is found in warm, sunny with the help of its chitinous foreleg or angle of about 1000 to conditions for optimal growth and reproduction. During rainy the thorax later it started digging and inserted its abdomen into season (June-August) its population reaches at peak. Because the hole. Then the female continued the movement of the of this adaptation to xeric life, their field mortality remains very anterior and posterior valves till the digging was complete, the low during the year. Maximum number of this pest was found wings touched the soil surface and the hind tibiae rested on the in the month of August to October after rain. Thereafter femora. During the process the abdomen increased in length population of the pest decllined gradually till February as cold as a result of stretching of intersegmental membrane. When weather suppressed metabolic activity of insects. It again the digging of hole into the sand was complete the female started to build up from month of March till month of April, emptied the frothy secretion of the accessory glands which afterwards it showed decline in the months of May and June formed a tube like structure and laid eggs in systematic way at due to further rise in temperature. The pooled data for the year right angles to the base of the oviposition hole. Females laid up 2010-2011 and 2011-2012 revealed that the population C. to 8 to 12 egg pods. The eggs were 7 to 8 mm in length and trachypterus had significant positive correlation with maximum freshly laid eggs were delicate and light yellow in colour, which and minimum temperature, rain fall and relative humidity. hardened and became dark brown later on. After laying, the Nymph population was negatively correlated (r= 1.291) with female retracted its abdomen and filled the upper portion of the maximum temperature which showed positive correlation (r= hole with more froth. On hardening the lower portion of the 4.836) with minimum temperature. Maximum and minimum froth formed the wall of the egg pod and the upper portion relative humidity (r= 8.636 and r= 12.172) and total rain fall formed the ’plug’ of the egg pod. This protects the egg pod and (r=5.94) revealed positive correlation with population of also serves outward way for hatching nymphs. The females nymphs [20]. finally covered the ‘plug’ of the egg pod by pushing the sand with help of the hind legs [20]. Biological description and identification of different hopper stages of C. trachypterus with special reference to its habitats Incubation period varied from 17 to 23 days with an and male and female genitalia have been described [24, 26]. average of 19.9±0.78 days. Early nymphs were pale yellow in Abdel Rahman [2] had made observations on embryology and colour and became dark brown later on. Nymphs were devoid physiology of C. trachypterus. The combination of body of wings but after maturation wings and genitalia developed coloration and pigmentation, the number of antennal very well. There were five and six instars in male and female, segments, the measurements of body parts and respectively. Duration of first nymphal instar ranged from 13 to comprehensive account on the life-history of C. trachypterus 17 days, with an average of 16.2±0.42 days. Duration of RRIJM 2015, All Rights Reserved 719 | P a g e Volume-03, Issue-12, December -2018 RESEARCH REVIEW International Journal of Multidisciplinary second nymphal instar lasted for 11 to 18 days with an occurred at 35°C and 80% relative humidity [27, 28] average of 14.3±0.44 days. Third instar nymph duration ranged temperature directly affected the incubation period of within the from 16 to 22 days with an average of 19.2±1.41 days. Fourth limits of favorable temperature [16, 19]. Females of C. instar nymph duration lasted for 18 to 25 days with an average trachypterus preferred 10% soil moisture to that of 4, 5 and of 21.5±1.45 days. In male fifth instar nymphs moulted into 6%. Among the soil types, sand was highly preferred for adult with well developed wings and genitalia. They possessed oviposition followed by red soil, coal ash and Badarpur sand dark brown color than previous instars. Length of fifth instar [7]. Isolated female of C. trachypterus laid more egg pods as nymph ranged from 0.9 to 1.2 cm with an average of 1.12 cm, compared to a female bred under crowded condition. Crowding whereas width ranged from 0.4 to 0.5 cm with an average of also affected the reproduction period and longevity [27]. The 0.42 cm, respectively. Average nymphal duration so recorded highest fertility of C. trachypterus was observed at fluctuating was 20.2±1.66 days ranging from 18 to 26 days. Sixth instar temperature (Av. 29.6° C). The mean number of copulations nymphs finally moulted into adult female. Length and width per female was recorded to be 8.2±2.4. The weight and size of were observed to be 1.26 and 0.64 cm, respectively. Duration eggs changed during incubation due to water absorption. The of sixth instar duration ranged from 13 to 22 days with an numbers of oviposition were highest (8.9±1.22) in soil with 15% average of 17.5±1.66 days [20]. Width of the head capsule in moisture. The female preferred to lay eggs in loose sand [3, 4, successive instars of C. trachypterus increased in regular 7]. The pre- oviposition period recorded was 12 to 23 days geometrical progression and proved that the progression of the and with a mean value of 18.1±1.11 days. Average oviposition line occurred within Dyar’s constant [32]. The average ratio of period was found to be 48.1±2.56 days which ranged from 34 increase in each instar was 1.185 for male hoppers having five to 60 days. The post-oviposition period varied from 10 to 24 instars. Similarly the average ratio of increase in head width days with an average of 19.8±1.32 days [20]. stood at 1.179 in females having six instars. Adult of C. trachypterus are medium in size, females are longer (bulky) Longevity of females was recorded from 71 to 93 days than males. They possess mandibulate mouth parts and fully with an average of 83.1±2.43 days. Male longevity lasted for developed wings. Head is hypognathous and antennae are 61 to 86 days with an average of 72.3±2.63 days as females filiform.